Vortex Flowmeters

Vortex Flowmeters

Vortex flowmeters measure volumetric flow by exploiting the predictable vortex shedding that occurs downstream of a bluff body placed in the flow stream. Above a minimum velocity, vortices form alternately on each side of the bluff body; the shedding frequency is proportional to mean flow velocity and therefore to volume flow. The pressure fluctuations created by these vortices are sensed and converted into a linear flow signal.

Because vortex technology is applicable to liquids, gases, and steam, it is widely used in utility and process services where a single meter type must cover varied media. Modern multivariable vortex meters extend beyond volumetric flow by incorporating temperature sensing and a flow computer to derive mass flow, which is particularly valuable for steam and compressible gases.

Benefits include broad media suitability, performance that is largely unaffected by changes in pressure, density, temperature, and viscosity, and strong long-term stability (no zero-point drift and a lifetime K‑factor are commonly cited). Typical turndown is about 10:1 to 30:1 for gas/steam and up to 40:1 for liquids, and designs are available for wide temperature ranges, including very low-temperature and high-temperature services. Endress+Hauser

Typical applications include chemical and petrochemical processes, power generation, and heat-supply systems with saturated or superheated steam. Gas services often include compressed air, nitrogen, liquefied gases, flue gas, and carbon dioxide; liquid services include demineralized water, solvents, heat-transfer oils, boiler feedwater, and condensate. Where steam quality is a concern, advanced devices can monitor wet-steam conditions and alarm on degraded quality, supporting more reliable energy accounting and equipment protection.

Engineering considerations include ensuring sufficient Reynolds number to sustain stable vortex shedding, evaluating sensitivity to mechanical vibration, and providing appropriate straight-run lengths to control upstream swirl and asymmetry. Like other bluff-body restrictions, some pressure loss is introduced and should be reviewed against available margin, particularly in low-pressure steam. Installation orientation, impulse from nearby control valves, and the expected range of fluid states (dry vs. wet steam) should be addressed during specification to maintain measurement robustness.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.